AIM: To observe different histomorphologic changes of ulcerative colitis (UC) rats that were treated with four regulating-intestine prescriptions (FRIP), to investigate the curative effects of FRIP and to analyze their treatment mechanism. METHODS: The UC rat model was made by the method of 2,4-dinitro chloro benzene (DNCB) immunity and acetic acid local enema. Ninety-eight SD rats were randomly divided into seven groups, namely, the normal control group, model group, salicylazosutfapyridine (SASP) group, Wumeiwan (WMW) group, Baitouwengtang (BTWT) group, Senglingbaishusan (SLBSS) group, and Tongxieyaofang (TXYF) group. Each group had 14 rats (with equal ratio of male and female). The six animal model groups of UC -SASP, TXYF, WMW, BTWT, SLBSS, TXYF-were treated by distilled water except the normal control group. Changes of the rat’s general conditions after treatment were respectively observed, the colon tissue damage scores were given out, the pathology of colonic mucosa and changes of ultrastructure were analyzed. RESULTS: Different pathological changes on histology were shown after treatment by FRIP. The colon tissue damage score in model group was higher than that of FRIP groups and SASP group (q = 4.59,4.77, P<0.05 or q=5.48, 6.25, 5.97, P<0.01). The scores of WMW group, BTWT group and SLBSS group were lower than that of SASP (q=4.13, P<0.05 or q=5.31, 5.12, P<0.01). There was no remarkable difference between the damage score of TXYF group and SASP group (q= 3.75, P>0.05). In addition, some apoptosis cells were found in the pathologic control group. CONCLUSION: The model made with DNCB and acetic acid was successful, and FRIP had better curative effect and WMW was the best curative effect, BTW, SLBSS and TXYF were similar to SASP, and we discovered that apoptosis was possibly related to UC. AIM: To observe different histomorphologic changes of ulcerative colitis (UC) rats that were treated with four regulating-intestine prescriptions (FRIP), to investigate the curative effects of FRIP and to analyze their treatment mechanism. METHODS: The UC rat model was made by Ninety-eight SD rats were randomly divided into seven groups, namely, the normal control group, model group, salicylazosutfapyridine (SASP) group, Wumeiwan ( Each group had 14 rats (with equal ratio of male and female). The six animal model groups of UC -ASP, TXYF, WMW group, Baitouwengtang (BTWT) group, Senglingbaishusan (SLBSS) group, and Tongxieyaofang (TXYF) WMW, BTWT, SLBSS, TXYF-were treated by distilled water except the normal control group. Changes of the rat’s general conditions after treatment were observed, the colon tissue damage scores were given out, the pathology of colonic mucosa and changes of ultrastructure were analyzed. RESULTS: Different pathological changes on histology were shown after treatment by FRIP. The colon tissue damage score in model group was higher than that of FRIP groups and SASP group (q = 4.59, 4.77, P <0.05 or q = 5.48, 6.25, 5.97, P <0.01). The scores of WMW group, BTWT group and SLBSS group were lower than that of SASP (q = 4.13, P <0.05 or q = 5.31, 5.12, P <0.01). no remarkable difference between the damage score of TXYF group and SASP group (q = 3.75, P> 0.05). CONCLUSION: The model made with DNCB and acetic acid was successful, and FRIP had better curative effect and WMW was the best curative effect, BTW, SLBSS and TXYF were similar to SASP, and we discovered that apoptosis was possibly related to UC.